1. Field of the Invention
This invention relates to a rotary stand for a video display, a telephone set or the like to be turned in any direction.
2. Description of Related Art
FIG. 1 illustrates a perspective view of a conventional rotary stand of the type referred to above. In FIG. 1, a turntable 1 is placed on a base 2. A circular face 2a is provided at the base 2, with an axis 2b projecting at the central part of the circular face 2a. The axis 2b is inserted into an elongated hole 1b formed in the turntable 1. A circular face 1a is formed in the turntable 1 in a manner to cover the elongated hole 1b, the lower surface of which is slidably put on the circular face 2a of the base 2. The circular faces 1a, 2a are held in tight contact with each other approximately all over the surfaces thereof as indicated in a cross sectional view of FIG. 2.
A cylindrical spacer 4 is fitted to the outer periphery of the axis 2b inserted into the elongated hole 1b, and has a flange portion 4a covering an upper edge of the elongated hole 1b. An axis part of a cylindrical stopper 3 with a flange portion 3a which covers the flange portion 4a is fitted into a central hole of the axis 2b within the spacer 4. The turntable 1 and base 2 are coupled by a screw 5 and a nut 6. The screw 5 is inserted into the stopper 3 and the central hole of the axis 2b from the upper right, and the nut 6 can be screwed to the screw 5 in the central hole of the axis 2b from the lower surface of the base 2.
The conventional rotary stand in the aforementioned structure will be used in a manner as will be depicted below. In the first place, the turntable 1 is placed onto the base 2 as the axis 2b is put into the elongated hole 1b, and the spacer 4 is fitted into between the outer periphery of the axis 2b and the elongated hole 1b. Moreover, the stopper 3 is inserted into an upper end of the central hole of the axis 2b. Finally, the base 2 is coupled with the turntable 1 by the screw 5 and the nut 6 thrust into an end part of the screw 5. If the nut and screw 5, 6 are screwed by a proper amount, the position of the circular faces 1a, 2a is optionally selected to achieve sliding contact therebetween. In other words, the circular face 1a becomes slidable to the circular face 2a in the whole 360.degree. area in the horizontal direction, and at the same time, in the vertical direction by the length of the elongated hole 1b . Accordingly, the turntable 1 is made possible to turn on the base 2 in the above area of the horizontal direction and able to sway in the above restricted range of the vertical direction.
An applied example of FIG. 1 is shown in FIG. 3. In the applied example, a head of a stopper 3A is formed rhombic. Moreover, a pair of ribs 20 are provided projecting at both sides of the elongated hole 1b, as indicated in FIG. 3(a). When the turntable 1 is turned in the horizontal direction on the base 2 as shown in FIGS. 3(b) and 3(c), a corner of the rhombic stopper 3A butts against one of the ribs 20, whereby the horizontal turn of the turntable 1 is restricted.
FIGS. 4 and 5 show the other example of the conventional rotary stand with a turn restricting mechanism, in which reference numerals 7-9 represent an upper table, a rotating table and a base, respectively. A circular recess 9a is formed at an upper surface of the base 9 to accommodate the rotating table 8. A stopper element 8a provided at the lower surface of the rotating table 8 is inserted into a circular guide groove 9b of fixed length at the bottom of the recess 9a. The rotating table 8 is turned while inserted into the recess 9a. A central hole 8c passes through the central part of a curved face 8b at the upper surface of the rotating table 8. A curved face 7b is formed at the lower surface of the upper table 7 in such a shape as to be slidable to the curved face 8b. An axis 7c projecting at a fixed plate 7a mounted onto the upper table 7 at a part corresponding to the curved face 7b is inserted inside the central hole 8c of the rotating table 8. A screw 10 is forced into the axis 7c via an assistant plate 10a at the lower surface of the base 9. The three members, i.e., upper table 7, rotating table 8 and base 9 are integrally coupled by this screw 10.
According to the above conventional example, the upper table 7 and rotating table 8 are held in contact with each other at the respective curved faces 7b, 8b, so that the upper table 7 is made slidable on the rotating table 8. Therefore, the upper table 7 is possible to sway in a vertical direction. On the other hand, the rotating table 8 is possible to turn around the axis 7c within the recess 9a of the base 9 in the range allowing the stopper element 8a to move in the guide groove 9b, that is, in the range allowing the stopper element 8a to butt against both ends of the guide groove 9b.
Because of the above-discussed structure of the conventional rotary stands, it is impossible in the case of FIGS. 1, 2 to control the turning amount of the turntable 1 to the base 2. If a function to control the turning amount is provided for the rotary stand of FIGS. 1, 2, the swaying angle of the turntable 1 in the vertical direction might be disadvantageously limited.
In the meantime, although it is possible in FIG. 3 to control the turning angle of the turntable 1 by making the corner of the rhombic stopper 3A hit the rib 20, the axis 2b, rib 20 or stopper 3A may be broken if the turntable 1 is turned with a large force.
Further, since the fundamental parts of the rotary stand shown in FIGS. 4, 5 are separated into three pieces, namely, upper table 7, rotating table 8 and base 9, the structure is undesirably bulky in size and complicated, thus inviting an increase of costs.
A similar example of the rotary stands in the structure as above is revealed in Japanese Utility Model Application Laid-Open No. 59-147375 (1984) as well.